Hmm, Dayton RS28F - F??? What have we here?

[dlr]

Re: Hmm, Dayton RS28F - F??? What have we here?

I wonder what the HF hash is all about on the RS28F at 2 kHz? Looks like something is buzzing but its way down in level.

There are a few other of Mark's measurements with some HF hash, Test Group 5 for example. I attributed that to something minor in his test rig, thinking it might be reflections from the mic clamp. All three drivers in this test group have it. Now that you mention buzzing, it does appear to be more of a ringing/buzzing signal intruding since reflections from the stand/clamp wouldn't ring that way.

What would be the influence of that on distortion measurements?

In the distortion measurements, there is a spike seen on all of the measurements that appears to be precisely at a subharmonic of 1/5 of the fundamental. It's in all of them and relatively high in level and few if any others are prominent, maybe only one in the Tang-Band.

Looking again, the relative level seems constant between all of them for the 1/5, the T-B the only one with any significant output in the other subharmonics. In Test Group 5, the LPG looks particularly bad, but the 1/5th is rather strong even in the SS6600.

Interestingly, the North Creek D28 has little between fundamental and 1/5 and at 1/5 it's lower in level than any of the others. To what can this be attributed?

What's the impact of the subharmonic as far as the relative ranking goes or is it simply to be ignored as an artifact of testing?

dlr

[Pete Schumacher]

Re: Hmm, Dayton RS28F - F??? What have we here?

I wonder what the HF hash is all about on the RS28F at 2 kHz? Looks like something is buzzing but its way down in level.

It's the noise from all those silk fibers rubbing together. ;)

Don't have the problem with 'luminum. :D

[DDF]

Re: Hmm, Dayton RS28F - F??? What have we here?

I've posted my results.

http://www.audioheuristics.org/measu...er_group_6.htm

I wonder what the HF hash is all about on the RS28F at 2 kHz? Looks like something is buzzing but its way down in level.

[dlr]

Re: Hmm, Dayton RS28F - F??? What have we here?

I've posted my results.

http://www.audioheuristics.org/measu...er_group_6.htm

Verrrrry interesting, Mark. The SB Acoustics blurb about better off-axis performance for the SB29 seems questionable. I suppose they're comparing to the SB25. The RS28F is clearly the winner and is overall more linear, though after equalization it's probably a wash.

For practical applications it does look like the only real difference is the top end directivity, at least for me, since I almost always use tweeters in systems that requre they be padded anyway. The one other very slight quality difference is the very small one in faceplate diameter, not enough to matter in my book. That and $1.25 more for the SB.

dlr

[Jim Holtz]

Re: Hmm, Dayton RS28F - F??? What have we here?

Great results!

Thanks Mark!

Jim

[markk]

Re: Hmm, Dayton RS28F - F??? What have we here?

I've posted my results.

http://www.audioheuristics.org/measurements/Testing/Tweeter6/tweeter_group_6.htm

[dlneubec]

Re: Hmm, Dayton RS28F - F??? What have we here?

Thanks for the effort, Mark!

[markk]

Re: Hmm, Dayton RS28F - F??? What have we here?

I've finished testing these but haven't posted a page yet.

You might as well buy a pair now.

Same motor as the metal dome RS28A's, double copper sleeve. Very smooth FR, gentle rise, easily correctable.

No ferrofluid.

Sensitivity ~90-91db/2.83v

Excellent distortion performance, on par with the metal dome (didn't directly compare the two yet-but looks usable to 1.3-1.5k)

I did not do off axis measurements. Er, I'll let DLR or Zaph do that. Probably not much different than any other 1" dome.

[critofur]

Re: Don't drink and drive (as in audio speaker driver)

It's the one inch distance that's doing it.

...Got to be more careful when doing speaker work late at night - oh - and, after having gone to "Five at Five" which is the local Whole Foods thing where you try five types of wine for $5 :P

I'll get the speaker up on a stand and take some higher level measurements from farther away...

[Jeff B.]

Re: Hmm, Dayton RS28F - F??? What have we here?

Here are measurements of both RS28A and RS28F on an 7" wide baffle, mic close (just under 1 inch away) at low level. They have a 2nd order elec. crossover consisting of a 1uf Cap + .35mH inductor. This crossover makes no sense to me - why is a 1uF letting so much low fr through? Might be something wrong with my measurement setup, will have to check it more thoroughly tomorrow. Anyway, for now, RED is the RS28A and black is the RS28F:

It's the one inch distance that's doing it.

[critofur]

Re: Hmm, Dayton RS28F - F??? What have we here?

Maybe it's a 10uF and you thought it says 1.0uF...?

No, I've got a box full of these 1uF caps, I've measured a bunch and they're very tight tolerance, I love 'em.

They say:

CM03
nt 1UF +/- 5%
200VDC=80M

They're more like +/- 1% :D

I'll hookup an amp and also use some other mics tomorrow, make sure the sound card settings are all good, measure some woofers also, etc... Oh, and I'll toss together some LspCAD simulations and see what it says too.

[envisionelec]

Re: Hmm, Dayton RS28F - F??? What have we here?

Here are measurements of both RS28A and RS28F on an 7" wide baffle, mic close (just under 1 inch away) at low level. They have a 2nd order elec. crossover consisting of a 1uf Cap + .35mH inductor. This crossover makes no sense to me - why is a 1uF letting so much low fr through? Might be something wrong with my measurement setup, will have to check it more thoroughly tomorrow. Anyway, for now, RED is the RS28A and black is the RS28F:

Maybe it's a 10uF and you thought it says 1.0uF...?

[critofur]

Re: Hmm, Dayton RS28F - F??? What have we here?

Here are measurements of both RS28A and RS28F on an 7" wide baffle, mic close (just under 1 inch away) at low level. They have a 2nd order elec. crossover consisting of a 1uf Cap + .35mH inductor. This crossover makes no sense to me - why is a 1uF letting so much low fr through? Might be something wrong with my measurement setup, will have to check it more thoroughly tomorrow. Anyway, for now, RED is the RS28A and black is the RS28F:

[critofur]

Re: Hmm, Dayton RS28F - F??? What have we here?

I took the plates off and switched the diaphragms. The motors look identical between the recent "non ferrofluid" RS28As that I have and the RS28Fs that I got. The F also does not have ferrofluid. The voice coils do not look to be of different length or at a different depth.

I did actually build a box, cut the baffle, and bring it inside to take some measurements - will measure both the A and F to post a comparison. Just something quick and easy for now. Hope to get to that in a bit, but maybe tomorrow.

And, I discovered an issue with one of my RS28As - the outer copper shorting ring on one of my tweeters was not pushed all the way down when it was manufactured. That tweeter was about 1db more sensitive than the other one, I wonder if it has something to do with the position of the shorting ring? I hope it won't limit x-max of the tweeter by touching the surround.

[PunkSweeper]

Re: Hmm, Dayton RS28F - F??? What have we here?

RSilkie.